Heating, cooking and sterilizing device

ABSTRACT

Hitherto, a cooking apparatus and a preservative food preparing apparatus have been known and practically used exclusively for the purpose of cooking foods or preparing preservative foods. There has been an increasing demand for a cooking-and-preservative food preparing apparatus.  
     To meet this demand, a heating, cooking, and sterilizing apparatus according to the present invention is constructed as follows: a horizontal type of cylindrical heating-and-cooking oven  1  has numerous nozzles  7  provided therein. These nozzles  7  are connected to the outlet  37  of a heat exchanger  25  positioned outside of the oven  1 , and the bottom of the oven  1  is connected to the inlet  38  of the heat exchanger  25  via a return pipe  43 , which is fixed to the bottom of the oven  1 , thus forming a circulation line between the oven  1  and the heat exchanger  25 . A circulation pump  40  is included in the circulation line. First and second tanks  42  and  51  are connected at their outlets to the drawing side of the circulation pump  40 , and at their inlets to the discharging side of the circulation pump  40  in such a way that the first and second tanks  42  and  51  may be selectively connected to the heat exchanger  25 . A washing water tank  67  is selectively connected to the first and second tanks  42  and  51 , and the oven  1  can be connected to a compressed air supply source  19  and an inert gas source. The oven is equipped with different sensors  9  to  12  for monitoring some factors. A control section is responsive to the signals from these sensors  9  to  12  for controlling the temperature of the heat exchanger  25  and the inner pressure of the oven  1 , and for permitting the nozzles  7  to eject an aqueous seasoning solution, steam, hot water or cooling water according to the software program installed in the control section.

TECHNICAL FIELD

[0001] The present invention relates to a cooking-and-sterilizingapparatus which can be equally used both in cooking foods by sprayingheated aqueous seasoning solutions directly on the foods for cooking andin preparing preservative cooked foods by heating, cooking, andsterilizing the foods that are preliminary sealed in bags or containers.

BACKGROUND ART

[0002] The inventor developed an apparatus for preparing inertgas-filled packages of preservative cooked foods by putting semi-cookedfoods along with seasonings in gas-impermeable bags, replacing the airwith nitrogen in the bags, and subjecting the foods stacked in the bagsto a series of thermal cooking and sterilizing steps for a short time,and the inventor filed a patent application for claiming the cooking andsterilizing apparatus for a patent (Republished Patent WO95/23526).Also, the inventor developed an apparatus for cooking foods directly byspraying hot aqueous seasoning solutions on raw materials, and theinventor filed a patent application for claiming the cooking apparatusfor a patent (Japan Patent Application Laid-Open No. H-11-253311).

[0003] These apparatuses, however, can be used exclusively for the solepurpose, and therefore, there has been an increasing demand for anapparatus which can be used commonly both in cooking foods and inpreparing preservative cooked foods.

[0004] The object of the present invention is to provide a heating,cooking, and sterilizing apparatus which is capable of cooking rawmaterials directly and of preparing preservative cooked foods.

DISCLOSURE OF INVENTION

[0005] To attain this object a heating, cooking, and sterilizingapparatus according to the present invention comprises:

[0006] a horizontal type of cylindrical heating-and-cooking oven havinga door provided on one end for putting in and taking out foods from theinside of the oven;

[0007] numerous nozzles arranged on the opposite sides of the inside ofthe oven and inner-directed toward the center of the oven;

[0008] a heat exchanger, the inlet of said heat exchanger beingconnected to the bottom of said oven via a return conduit, and theoutlet of said heat exchanger being connected to said nozzles so that acirculation line may be formed between said heat exchanger and saidoven;

[0009] a circulation pump placed in the circulation line;

[0010] first and second tanks whose outlets and inlets can beselectively connected to the drawing and discharging sides of saidcirculation pump;

[0011] a washing water tank which can be selectively connected to saidfirst and second tanks via an associated washing water pump;

[0012] a compressed air source, a nitrogen gas tank and a vacuum pump,all of which are connected to said oven;

[0013] a temperature sensor for detecting inner temperature of the saidoven, a center temperature sensor for detecting center temperature offoods, and an inner pressure sensor for detecting inner pressure of thesaid oven, all equipped with said oven; and

[0014] a control section for controlling the temperature and pressure ofsaid oven in response to the signals from said temperature sensors andpressure sensor, and for permitting said inner-directed nozzles to ejectaqueous seasoning solutions, hot water, or cooling water according tothe software program installed in the control section.

[0015] When the apparatus works in the direct cooking mode that cooksfoods directly by spraying hot aqueous seasoning solutions on rawmaterials, said first tank containing an aqueous seasoning solution isconnected to said circulation line, and said control section hasfunctions of: allowing the aqueous seasoning solution to circulate insaid circulation line; spraying the aqueous seasoning solution on thefood in said oven while controlling the inner pressure of said oven andthe temperature of said heat exchanger in response to the signals fromsaid temperature sensors and pressure sensor; allowing the aqueousseasoning solution to circulate between said heat exchanger and saidoven; and bringing the aqueous seasoning solution back to said secondtank after finishing the required cooking.

[0016] When the apparatus works in the preservative food-preparing modethat cooks and heat-sterilize prepackaged foods, said first tank isfilled with hot water and at the same time said second tank is filledwith cold water, and said control section has functions of: supplyingsaid oven with the hot water from said first tank, and supplying saidoven with the cold water from said second tank to cool said ovensubsequent to termination of the cooking and sterilizing of theprepackaged foods with heat of the hot water, while controlling theinner pressure of said oven and the temperature of said heat exchangerin response to the signals from said temperature sensors and pressuresensor.

BRIEF DESCRIPTION OF DRAWINGS

[0017]FIG. 1 is a side view of a heating, cooking, and sterilizingapparatus;

[0018]FIG. 2 is a front view of the heating, cooking, and sterilizingapparatus with its door open;

[0019]FIG. 3 shows how the parts of the apparatus are connected to eachother; and

[0020]FIG. 4 illustrates the piping in the oven.

BEST MODE FOR CARRYING OUT THE INVENTION

[0021] Referring to FIG. 1, a heating, cooking, and sterilizingapparatus according to one embodiment of the present invention comprisesa horizontal type of cylindrical heating-and-cooking oven 1. It has adoor or circular cover plate 3 provided on its front side for putting inand taking out foods from the inside of the oven. The oven 1 is closedon its rear side. The circular cover plate 3 is shown as closing thefood inlet/outlet 2 of the oven 1.

[0022] A food carrier 4 has wheels 4 a and a plurality of food shelves 4c arranged in its frame. It can move on a pair of rails 4 b laid on thebottom inside the oven 1.

[0023] Numerous feeding pipes 6 are arranged vertically, and are closedat their top ends. As seen from FIG. 2, these feeding pipes 6 standupright on the opposite sides of the inside of the oven 1 and penetratethe oven 1. Numerous nozzles 7 are fixed to the feeding pipes 6 anddirected toward foods on the food shelves 4 c of the food carrier 4 inthe oven 1.

[0024] The cover plate 3 has a watching window 8 for watching the insideof the oven 1, and the oven 1 is equipped with a pressure sensor 9, atemperature sensor 10, a center temperature sensor 11, and a nitrogendensity detecting sensor 12.

[0025] Various devices as seen in FIG. 3 are connected to the oven 1.

[0026] The oven 1 has an air outlet 13 made in its ceiling, and theinside of the oven 1 is connected to a vacuum pump 15 via anopening/closing valve 14.

[0027] Also, the oven 1 has a gas inlet 16 made in its ceiling, thuspermitting the oven 1 to be supplied with nitrogen or compressed airfrom an inert gas supply tank 18 and an air supply tank 19 via anopening/closing valve 17.

[0028] The inert gas supply tank 18 and the air supply tank 19 areconnected to the gas inlet 16 of the oven 1 via associatedopening/closing valves 20 and 21.

[0029] As seen from FIGS. 2 and 4, the feeding pipes 6 standing uprighton the opposite sides of the inside of the oven 1 are connected at theirlower ends to horizontal branch pipes 22, which are laid outside of theoven 1. All branch pipes 22 are connected to a trunk pipe 23, which isconnected to the outlet side 37 of the heat exchanger 25 via anopening/closing valve 24.

[0030] Placing the branch and trunk pipes 22 and 23 outside of the oven1 permits expansion of the space available inside of the oven 1 to theextremity. Also, distribution of nozzles 7 on the numerous branch pipes22 assures that the pressures be equalized in all nozzles 7.

[0031] A cooling water supply tank 28 is connected to the thermal mediuminlet 26 of the heat exchanger 25 via an associated pump 64 and anopening/closing valve 27, and a steam supply source 31 is connected tothe thermal medium inlet 26 of the heat exchanger 25 via associatedopening/closing valves 29 and 30. A cooling water withdrawal tank 34 isconnected to the thermal medium outlet 32 of the heat exchanger 25 viaan associated opening/closing valve 33.

[0032] The steam supply 31 is connected to the trunk pipe 23 viaopening/closing valves 29 and 61, and via an opening/closing valve 69and a superheated steam generator 70.

[0033] A first tank 42 is connected to the inlet 38 of the heatexchanger 25 via an associated opening/closing valve 41, a pump 40, andan opening/closing valve 39.

[0034] A return conduit 43 is connected on one end to the bottom of theoven 1, and on the other end to the pump 40 via an opening/closing valve44, and to a drain pipe 46 via an associated opening/closing valve 45.

[0035] A filter 47 is placed on the upstream side of the pump 40,removing foreign substances from the liquid discharged from the returnconduit 43.

[0036] An aqueous seasoning solution tank 48 is connected to the firsttank 42 via an associated pump 49 and opening/closing valve 50,supplying the first tank 42 with thick aqueous seasoning solution tocontrol the density of the aqueous seasoning solution contained therein.

[0037] A second tank 51 is connected to the outlet 37 of the heatexchanger 25 via an associated opening/closing valve 52, and isconnected to the pump 40 via an associated opening/closing valve 65.

[0038] A water supply source 53 is connected to the first tank 42 viaassociated opening/closing valves 54 and 55 to reduce the density of theaqueous seasoning solution in the first tank 42. Also, the water supplysource 53 is connected to the second tank 51 via associatedopening/closing valves 54 and 56 to supply the second tank 51 withcooling water.

[0039] A washing water tank 67 is connected to the first tank 42 via anassociated pump 66 and opening/closing valves 68 and 55. Also, it isconnected to the second tank 51 via associated opening/closing valves 68and 56. Thus, the first and second tanks 42 and 51 can be supplied withwashing water when occasions demand.

[0040] The first and second tanks 42 and 51 are connected to associateddrain pipes 57 and 58 via opening/closing valves 59 and 60 respectively.

[0041] The oven 1 is connected to a vent 62 via an associatedopening/closing valve 63.

[0042] The manner in which a given food material is cooked directly inthe heating, cooking, and sterilizing apparatus is described below:perforated trays 5 containing the food material such as soy beans orblack soy beans are put on the shelves 4 c of the wheeled carrier 4. Thecircular cover plate 3 of the oven 1 is opened and the wheeled carrier 4is put on the rails 4 b in the oven 1 to be pushed in the oven 1 throughthe food inlet/outlet 2.

[0043] Then, the cover plate 3 is closed, and the oven 1 is suppliedwith hot water. Thus, the food material is softened, and at the sametime, its harshness is removed. The hot water is supplied from the heatexchanger 25, in which the water from the first tank 42 is heated.

[0044] Specifically, the opening/closing valves 41 and 39 are opened toallow the pump 40 to move water from the first tank 42 to the heatexchanger 25. At the same time, the opening/closing valves 29 and 30 areopened to allow the steam supply source 31 to supply the steam to thethermal medium inlet 26 of the heat exchanger 25, thereby producing hotwater by heating the water from the first tank 42.

[0045] The hot water is made to flow in the opening/closing valve 24,the trunk pipe 23, the branch pipes 22, and the feeding pipes 6,allowing the inner-directed nozzles 7 to spray the hot water on the rawfood materials on the carrier 4. Each nozzle 7 has a slot formed on itsoutlet, causing the hot water to fan out and spread a relatively widerange.

[0046] The opening/closing valve 41 is closed, and the opening/closingvalve 44 is opened.

[0047] The hot water falling and remaining on the bottom of the oven 1is drawn by the pump 40 to flow back to the heat exchanger 25 via thereturn pipe 43, the opening/closing valve 44, and the filter 47, andthen, the hot water returns to the oven 1 after being reheated in theheat exchanger 25.

[0048] After finishing the softening and harshness-removing of the rawfood material, the opening/closing valves 29 and 30 upstream of thethermal medium inlet 26 of the heat exchanger 25 are closed, and at thesame time, the hot water is drained from the drain pipe 46. Then, theopening/closing valves 41, 39, and 24 are opened, and the pump 40 ismade to start, thereby supplying the oven 1 with the water from thefirst tank 42. The opening/closing valves 27 and 33 are opened to supplythe cold water from the cold water tank 28 to the thermal medium inlet26 of the heat exchanger 25. Thus, the water from the first tank iscooled in the heat exchanger 25 to be directed to the oven 1 for coolingthe inside of the oven 1.

[0049] After cooling the inside of the oven 1 the water is drained fromthe oven 1 through the drain pipe 46, and then fresh water is suppliedfrom the first tank 42 to the oven 1, so that the water is sprayed onthe food for washing. Used water is drained through the drain pipe 46.Washing can be repeated two or more times to meet occasional demand.

[0050] After washing the inside of the oven 1, the first tank 42, in itsturn, is washed with the washing water from the washing water tank 67,and then it is supplied with the aqueous seasoning solution from theaqueous seasoning solution tank 42. The heat exchanger 25 is suppliedwith the steam from the steam supply source 31 to heat the aqueousseasoning solution in the heat exchanger 25. The aqueous seasoningsolution thus heated is supplied to the feeding pipes 6 in the oven 1via the branch pipe 22 to be sprayed on the food from the nozzles 7.

[0051] Thus, the food in the oven 1 is exposed evenly to the hot mist ofseasoning so that the food may be heated, seasoned, and cooked.

[0052] The aqueous seasoning solution remaining on the bottom of theoven 1 flows through the return pipe 43 to be circulated as is the casewith circulation of the hot water as described above.

[0053] After cooking the food, the aqueous seasoning solution iscollected in the second tank 51 and the cover plate 3 is opened to pullthe carrier 4 bearing the cooked food out of the oven 1.

[0054] In preparing “Teriyaki chickens (chickens broiled with soy)”,chickens are seasoned and exposed to the mist of the superheated steam.Specifically the inside of the oven 1 is depressurized by allowing thevacuum pump 15 to draw the air from the inside of the oven 1, and thenthe opening/closing valves 17 and 20 are opened to supply the oven 1with the inert gas from the gas supply tank 18. Thus, the air in theoven 1 is replaced by the inert gas.

[0055] Then, the opening/closing valves 69 and 61 are opened, and theopening/closing valves 29 and 30 are closed. Thus, the steam from thesteam supply source 31 is superheated by the superheated steam generator70, and the so superheated steam is supplied directly to the feedingpipes 6 to be sprayed on the food.

[0056] “Seasoned, boiled soy beans” can be prepared as follows:

[0057] 1) Pre-Treatment: soy beans are soaked in water for 7 to 10hours.

[0058] 2) Removal of Harshness and Softening: pre-treated soy beans arecontained in small perforated trays, and the small perforated trays thusfilled with pre-treated soy beans are laid on each other in the oven 1.Cold water is directed from the cooling water supply tank 28 to thesecondary side of the heat exchanger 25, and the superheated steam isdirected to the primary side of the heat exchanger 25, thus providinghot water of 108° C. on the secondary side of the heat exchanger 25. Thehot water thus produced is directed to the feeding pipes 10 to besprayed from the nozzles 12 on the soy beans in the small perforatedtrays for 8 minutes. Thus, harshness is removed from the soy beans, andthe soy beans are softened.

[0059] 3) Cooling: cold water is directed to the primary side of theheat exchanger 25 to cool the hot water on the secondary side of theheat exchanger 25. The cooled water is sprayed on the harshness-free,softened soy beans in the small perforated trays for 5 minutes.

[0060] 4) Washing: cold water is directed from the cooling water supplytank 28 to be circulated in the circulation line, and the cold water isdrained in 5 minutes. This washing is repeated three times.

[0061] 5) Seasoning: an aqueous seasoning solution is directed to thesecondary side of the heat exchanger 25 while the superheated steam isdirected to the primary side of the heat exchanger 25. The aqueousseasoning solution of 100° C. is sprayed on the soy beans in the smallperforated trays for 20 minutes.

[0062] 6) Cooling: cold water is directed to the primary side of theheat exchanger 25, thereby lowering the temperature of the aqueousseasoning solution to about 40° C. in 10 minutes. Thus, the food can betaken out from the oven 1.

[0063] 7) Taking Out: the seasoned, boiled soy beans are taken out fromthe oven 1.

[0064] “Seasoned, boiled cubic pork” can be prepared as follows:

[0065] 1) Removal of Lard: cubic pieces of pork are contained in smallperforated trays, and the small perforated trays thus filled with cubicpieces of pork are laid on each other in the oven 1. Cold water isdirected from the cooling water supply tank 28 to the secondary side ofthe heat exchanger 25, and the superheated steam is directed to theprimary side of the heat exchanger 25, thus providing hot water of 100°C. on the secondary side of the heat exchanger 25. The hot water thusproduced is directed to the feeding pipes 10 to be sprayed from thenozzles 12 on the cubic pieces of pork in the trays for 60 minutes.

[0066] 2) Cooling: cold water is directed to the primary side of theheat exchanger 25 to cool the hot water on the secondary side of theheat exchanger 25. The cooled water is sprayed on the cubic pieces ofpork in the small perforated trays for 5 minutes.

[0067] 3) Washing: cold water is directed from the cooling water supplytank 28 to be circulated in the circulation line, and the cold water isdrained in 5 minutes. This washing is repeated three times.

[0068] 4) Seasoning: the inside of the oven 1 is depressurized, and thenan aqueous seasoning solution is directed to the secondary side of theheat exchanger 25 while the superheated steam is directed to the primaryside of the heat exchanger 25. The aqueous seasoning solution of 70° C.is sprayed from the nozzles 7 onto the cubic pieces of pork in the smallperforated trays for 20 minutes.

[0069] 5) Cooling: cold water is directed to the primary side of theheat exchanger 25, thereby lowering the temperature of the aqueousseasoning solution to about 40° C. in 10 minutes.

[0070] 6) Taking Out: the seasoned, boiled cubic pieces of pork aretaken out from the oven 1.

[0071] “Broiled sweet chestnuts” can be prepared as follows:

[0072] Pre-treated sweet chestnuts are contained in small perforatedtrays, and the small perforated trays thus filled with sweet chestnutsare laid on each other in the oven 1. Cold water is directed from thecooling water supply tank 28 to the secondary side of the heat exchanger25, and the superheated steam is directed to the primary side of theheat exchanger 25, thus providing hot water of 100° C. on the secondaryside of the heat exchanger 25. The hot water thus produced is directedto the feeding pipes 10 to be sprayed from the nozzles 12 on the sweetchestnuts in the small perforated trays for 1 minute. Then, the innerpressure of the oven 1 is lowered, and the oven is cooled for 15minutes.

[0073] The food thus treated or cooked has been sterilized primarily,and therefore, it can be packaged by inserting it in KOP or othergas-barrier bags or containers. The so packaged food can be stored 15 to20 days long in preservative condition if it is put in a refrigeratingshowcase (3° C.), and 3 months long in preservative condition if it isput in a deep-frozen condition (minus 20° C.).

[0074] If the cooked food is to be subjected to the secondarysterilization, the food is packaged by putting it in analumina-laminated synthetic resin bag, and the so packaged food issubjected to a low-temperature sterilization (90° C.). The so sterilizedfood can be preserved one to two months long at normal temperature.

[0075] Assuming that the apparatus according to the present inventionworks in the preservative food-preparing mode and sterilizes the cookedfood as hereinafter described, the food thus prepared can be preservedthree to twelve months long at normal temperature.

[0076] The apparatus according to the present invention has an advantagethat its operating mode can be switched swiftly from the direct cookingmode to the sterilizing mode so that both cooking and sterilizing offood can be performed in the same apparatus.

[0077] When the apparatus works in the preservative food-preparing mode,the first tank 42 is filled with hot water, and the second tank 51 isfilled with cold water. Then, the inner pressure of the oven 1 iscontrolled appropriately, and the hot water from the first tank 42 isheated still higher in the heat exchanger 25 before being supplied tothe feeding pipes 6.

[0078] In case that the apparatus is switched from the direct cookingmode to the preservative food-preparing mode, the remaining aqueousseasoning solution is drained from the first tank 42, and then the firsttank 42 is supplied with washing water from the washing water tank 67for rinsing. The required rinsing is effected automatically whenswitching to the preservative food-preparing mode. Finally the firsttank 42 is filled with hot water.

[0079] The temperature of the hot water is controlled in the followingorder: first, the 100° C. -high hot water is circulated (primarytemperature-rising step); second, the hot water is allowed to remain atthe temperature of 100° C. for a while (constant temperature-keepingstep); and third, the 125° C.-high hot water is circulated (sterilizingstep).

[0080] Thereafter, the opening/closing valves 29 and 30 upstream of thethermal medium inlet 26 of the heat exchanger 25 are closed, and theopening/closing valves 27 and 33 are opened to supply the cold waterfrom the cold water tank 28 to the thermal medium inlet 26 of the heatexchanger 25 by using the pump 64. Thus, the temperature of thecirculating hot water is lowered so that the food may be cooled to theextent of permitting the food to be taken out of the oven 1. Then, thehot water is collected to the first tank 42. The opening/closing vale 65is opened to supply the cold water from the second tank 51 to thefeeding pipes 6, thereby effecting the secondary cooling of the food.

[0081] A microcomputer (not shown) is responsive to the signals from theinner pressure sensor 9, the temperature sensor 10, and the centertemperature sensor 11 for effecting a series of controlling operationsaccording to the sequencer program as described above.

[0082] For example, in preparing “beef and burdock lightly broiled withsoy”, first, sliced pieces of burdock are put in a 60° C.-high weak acidbath for 30 minutes, and the so treated sliced pieces of burdock isblanched in a 160° C.-high oil for ten seconds.

[0083] A lump of frozen beef is defrosted and sliced, and the slicedpieces of beef are blanched in a 180° C.-high oil for five to tenseconds as a preliminary treatment.

[0084] The sliced pieces of burdock and beef thus blanched are mixedtogether, and are packaged by putting predetermined quantities ofbeef-and-burdock mixture in gas-impermeable bags and by replacing theair by an inert gas in the bags to be sealed The so packaged food issubjected to a multi-stage sterilization, which is composed of: heatingat the temperature of 102° C. for 20 minutes; heating at the temperatureof 110° C. for 10 minute; and heating at the temperature of 120° C. for5 minutes. Then, the sterilized food is cooled, and is marketed.

[0085] “Lightly seasoned, boiled vegetables” can be prepared as follows:pre-treated pieces of vegetables are weighed to be put in gas-barriercontainers. The air is replaced by an inert gas in all containers, andthen they are sealed. The gas-tight sealed containers are subjected to amulti-stepped treatment of heating-and-sterilizing, 102° C. for 30minutes and 110° C. for 10 minutes. Then, the sterilized food is cooled,and is marketed.

[0086] “yellowtail broiled with soy” can be prepared as follows:pre-treated sliced pieces of yellowtail are weighed to be put ingas-barrier containers. The air is replaced by an inert gas in allcontainers, and then they are sealed. The gas-tight sealed containersare subjected to a multi-stepped treatment of heating-and-sterilizing,100° C. for 5 minutes, 110° C. for 30 minutes, and 115° C. for 10minutes. Then, the sealed containers are cooled, and are marketed.

[0087] In the embodiment as described above, the first tank 42 isdescribed as being used to contain an aqueous seasoning solution, wateror hot water, and the second tank 51 is described as being used tocontain an aqueous seasoning solution or cooling water collected fromthe oven 1. Two tanks may be added, and the total of four tanks may beallotted to the aqueous seasoning solution, hot water, collected aqueousseasoning solution, and cooling water. This makes it unnecessary tochange the liquid in the tank and therefore the switching to analternative mode will be expedited.

[0088] Nitrogen is used as an inert gas to be provided in the oven 1,and accordingly the nitrogen density detecting sensor 12 is used.Carbonic acid gas, however, may be equally used, and then, a carbonicacid gas sensor may be used instead of the nitrogen density detectingsensor 12.

INDUSTRIAL APPLICABILITY:

[0089] In a heating, cooking, and sterilizing apparatus according to thepresent invention; a horizontal type of cylindrical heating-and-cookingoven has a door provided on one end for putting in and taking out foodsfrom the inside of the oven, and numerous nozzles provided on theopposite sides of the inside of the oven and inner-directed toward eachother. These nozzles are connected to the outlet of a heat exchangerpositioned outside of the oven, and the bottom of the oven is connectedto the inlet of the heat exchanger via a return pipe, which is fixed tothe bottom of the oven, thus forming a circulation line between the ovenand the heat exchanger. A circulation pump is included in thecirculation line, and first and second tanks are connected at theiroutlets to the drawing side of the circulation pump, and at their inletsto the discharging side of the circulation pump in such a way that thefirst and second tanks may be selectively connected to the heatexchanger. A washing water tank is selectively connected to the firstand second tanks via an associated pump, and the oven can be connectedto a compressed air supply source, a nitrogen gas tank and a vacuumpump. The oven is equipped with a temperature sensor, a centertemperature sensor, and an inner pressure sensor, and, the temperatureand pressure of the oven are controlled in response to the signals fromthese sensors. The nozzles are permitted to spray on the food an aqueousseasoning solution, steam, hot water, or cooling water according to thesoftware program installed in the control section.

[0090] The heating, cooking, and sterilizing apparatus can be used intwo different working modes, that is, direct food-cooking mode andpreservative food-preparing mode, thus doubly expanding the horizon ofuse.

1. A heating, cooking, and sterilizing apparatus comprising: ahorizontal type of cylindrical heating-and-cooking oven having a doorprovided on one end for putting in and taking out foods from the insideof the oven; numerous nozzles arranged on the opposite sides of theinside of the oven and inner-directed toward the center of the oven; aheat exchanger, the inlet of said heat exchanger being connected to thebottom of said oven via a return conduit, and the outlet of said heatexchanger being connected to said nozzles so that a circulation line maybe formed between said heat exchanger and said oven; a circulation pumpplaced in the circulation line; first and second tanks whose outlets andinlets can be selectively connected to the drawing and discharging sidesof said circulation pump; a washing water tank which can be selectivelyconnected to said first and second tanks via an associated washing waterpump; a compressed air source, a nitrogen gas tank and a vacuum pump,all of which are connected to said oven; a temperature sensor, a centertemperature sensor, and an inner pressure sensor all equipped with saidoven; and a control section for controlling the temperature and pressureof said oven in response to the signals from said temperature sensorsand pressure sensor, and for permitting the nozzles to eject aqueousseasoning solutions, hot water, or cooling water according to thesoftware program installed in the control section.
 2. A heating,cooking, and sterilizing apparatus according to claim 1, wherein saidfirst tank containing an aqueous seasoning solution is connected to saidcirculation line, and said control section has functions of: allowingthe aqueous seasoning solution to circulate in said circulation line;spraying the aqueous seasoning solution on the food in said oven whilecontrolling the inner pressure of said oven and the temperature of saidheat exchanger in response to the signals from said temperature sensorsand pressure sensor; allowing the aqueous seasoning solution tocirculate between said heat exchanger and said oven; and bringing theaqueous seasoning solution back to said second tank after finishing therequired cooking.
 3. A heating, cooking, and sterilizing apparatusaccording to claim 1, wherein said first tank is filled with hot waterand at the same time said second tank is filled with cold water, andsaid control section has functions of: supplying said oven with the hotwater from said first tank, and supplying said oven with the cold waterfrom said second tank to cool said oven subsequent to termination of thecooking and sterilizing, while controlling the inner pressure of saidoven and the temperature of said heat exchanger in response to thesignals from said temperature sensors and pressure sensor.